1. Field of the Invention
The present invention relates generally to measuring devices, and in particular, is concerned with a measuring apparatus for determining the weight of sliver.
2. Description of the Related Art.
In the textile industry, loose, untwisted fibers, such as cotton, worsted or wool, are manipulated during a carding process to form sliver. Sliver is generally coiled into and stored in cans or drums prior to spinning or other processes before being made into yarn.
For a carding process, it is desirable to know the weight per unit length of the sliver. Conventionally, this value has been determined by the use of strain gauges. After carding, the sliver is passed through a funnel, commonly known as a trumpet, which is mounted on and supported by a rigid plate, e.g. a steel plate. Electrically resistive type strain gauges mounted on the plate sense deflections caused by the sliver. The deflection sensings are translated into unit weight measurements by wiring the strain gauges in a Wheatstone Bridge configuration all of which is fully described in applicant's prior U.S. Pat. No. 4,823,597.
A particular problem with the above-described prior art measuring technique is that the plate is subject to external vibrations and other deflections which cause inaccurate measurements. For example, heavy equipment traveling near the measuring apparatus can impart vibrations to the plate which are sensed by the strain gauges and result in erroneous measurements.
Applicant's improved sliver measuring apparatus described in his prior U.S. Pat. No. 4,823,597 provides measurements free of error due to external vibrations and thus represents a significant improvement over the prior art. However, experience gained with the improved sliver measuring apparatus has indicated a further need for preventing damage in the event of an overload. In this regard it is to be noted that a normal load on the trumpet will cause no damage to the trumpet's mounting plate whereas an excess load on the trumpet mounting plate has been found to cause damage particularly to the portion of reduced cross section where the sensors are mounted. In this event the measuring apparatus has to be either repaired or discarded depending on the extent of damage. Other prior art relevant to the invention is described in U.S. Pat. No. 4,823,597.
The present invention thus has as its primary object that of providing a sliver measuring apparatus capable of rendering error free measurements in the event of external vibrations while at the same time also being capable of dealing with transient overloads on the trumpet without causing permanent damage to the trumpet mounting plate. Other objects will appear as the description proceeds.